Italian Pat. No. 685,844, for example, describes a device of the aforesaid type which has been used with advantage by numerous manufacturers. However, this device, which comprises a planet gear and two sun gears, has certain drawbacks, such as:
(1) the danger of the necessary lubrication of the parts subject to sliding friction damaging the roving; PA1 (2) inaccuracy in the centering of the epicyclic gears; PA1 (3) wearing of the epicyclic gear seats by the hardened steel of the bearings; PA1 (4) considerable energy consumption; PA1 (5) noise; and PA1 (6) the need for frequent maintenance. PA1 (1) The sliding friction couplings between the sun gears and planet gear are replaced by revolving friction couplings, using ball or roller bearings (i.e. rolling bearings), disposed with their axes vertical, said bearings having an inner ring and an outer ring (or race) as is conventional. PA1 (2) In general a bearing is not required to perform more than one function, i.e., from working simultaneously as a thrust, axial or supporting, and a centering, radial, bearing. PA1 (3) Instead of single bearing, the use of two equivalents is preferred to reduce the overall size of the device. PA1 (4) Bearings are used having an outer ring previously coated with self-lubricating resin, e.g. nylon 66, i.e., poly(hexamethylene adipamide), the bearings being preferably of lubrication sealed type. (Lubrication which could damage the roving is therefore dispensed with, and wear of the epicyclic gear seats and noise are considerably reduced.) PA1 (5) Three pairs of bearings disposed at 120.degree. to each other are used for supporting and centering the planet gear (see bearings 5 and 6 as shown in FIGS. 4 and 5), each pair being provided with a centering bearing and a thrust bearing. PA1 (6) Three pairs of bearings (see bearings 7 as shown in FIG. 3) disposed at 120.degree. to each other are used for supporting the first sun gear which engages with the planet gear, the bearings being arranged to resist downward thrusts and to center said sun gear. PA1 (7) Three pairs of thrust bearings (see bearings 11 as shown in FIG. 6) arranged at 120.degree. to each other are used for supporting the second sun gear, the bearings being arranged to support vertical stresses in both directions. PA1 (8) Three centering bearings (see bearings 12 as shown in FIG. 7) disposed at 120.degree. to each other are used for centering the roving turnplate (see disc 8 as shown in FIG. 2). PA1 (9) Three centering bearings disposed at 120.degree. to each other are used for centering the lower disc (disc 13 as shown in FIG. 2) surrounding the roving turnplate (disc 8 shown in FIG. 2). These bearings need not be coated. PA1 (10) A plate with inwardly inclined raised edges is disposed on the planet gear for collecting the roving waste, dust, etc. PA1 (11) The axial bearings used in this application show a resin coated outer ring tapered outwardly with an angle of 20.degree.-30.degree.. These limits depend on that if the angle is less than 20.degree. the coating wears too quickly, if it is greater than 30.degree. difficulties are encountered in maintaining a good centering action. These effects occur sharply beyond said 20.degree. and 30.degree..